The United Nations says recent military activity along the Kenya-Somalia border is restricting famine relief efforts and preventing Somalis from fleeing to refugee camps in Kenya.

The U.N. Refugee Agency said Wednesday that only 100 Somali refugees entered Kenya last week, down from 3,400 in the previous week.

Last week, Kenya sent troops across the border to hunt down Somali militants, who Kenya blames for a series of cross-border kidnappings.

The U.N. says the military build-up is causing anxiety among the civilian population, and is likely to restrict the movement of humanitarian personnel and supplies.

The organization says approximately 3.7 million Somalis are still in need of emergency food aid as a result of the region's worst famine in decades.

The report also notes that the unrest may have forced many Somali refugees to instead flee to Ethiopia, where the number of Somali arrivals in refugee camps significantly increased in the first part of October.

The agency says the reduction of refugee flow to Kenya could also be affected by the onset of heavy rains at the border.